Free piston well pump device



Sept. 29, 1964 D. e. KNOX FREE PISTON WELL PUMP DEVICE F l G. 3.

DONALD s. KNOX INVENTOR.

ATTORNEYS.

mx wdw w. -l{l M A z 1/ Jl lZ IIV/l/l/ V J 5 .1 4 F niuwmanuww4mmr e o M.l o w 2 m w 2 F I AW I V 0 I aw W 3/ 2 w m w m3 m m United StatesPatent 3,150,596 FREE PISTON WELL PUMP DEVICE Donald G. Knox, Box 458,Rolling Hills, Calif. Filed Oct. 10, 1961, Ser. No. 144,231 7 Claims.(Cl. 103-52) This invention relates to a free piston pump apparatus forraising fluid from a well by means of fluid pressure acting on saidpiston which travels the length of the eduction tube. This invention ismore particularly directed to improvements in devices of the type shownin my Patent No. 2,642,002 dated June 16, 1953.

One of the difficulties encountered in the operation of these pumpingdevices is the frequent inability of the free piston or plunger to reachthe bottom of the well with sufficient speed. This is especially true atdepths of 10,000 feet or more. The plunger is required to descend in theeduction tube under the forces of gravity. However when a high viscositywell fluid is encountered, the plunger may descend so slowly that it maynot make the required cycles per day to obtain maximum production. Theresult is a reduction in amount of formation fluid raised to thesurface.

It is the principal object of this invention to provide a free pistonpumping device employing a novel form of weighted element or sinker barto aid the free piston or plunger in descending in the eduction tubethrough high viscosity well fluid.

Another object is to provide such a Weighted element with an externalhelical fin to promote rapid descent of the plunger through such wellfluid.

It is more specifically an object of this invention to provide a freepiston pumping device having a weighted element which can be articulatedto allow its easy passage through sections of the eduction tube whichare not straight, said element being of suflicient mass to speed thedescent of the piston in a highly viscous fluid medium.

It is also the object of this invention to provide a free piston with aWeighted element so that the piston can descend against a large volumeof gas, such as in freecycling both in oil and gas wells Other importantfeatures and advantages which are believed to be novel are set forth inthe appended claims. The invention itself, and further advantagesthereof, may be more readily understood when read in connection with theaccompanying drawings, in which:

FIGURE 1 is a partial sectional side elevation of a well installationhaving an eduction tube and an improved embodiment of the free pistondevice therein.

FIGURE 2 is a partial sectional side elevation of the free piston orplunger taken substantially along line 22 of FIGURE 1.

FIGURE 3 is a sectional plan view of the sinker bar taken along line 33of FIGURE 2.

Referring now to the drawings, the free piston assembly generallydesignated is positioned within a sectional eduction tubing 11 whichextends into a well bore 12. The bore may be provided with the usualcasing 13. Gas under pressure may be admitted through valve 14, ifdesired to supplement formation gas, and passes downwardly in theannulus 15 between the casing 13 and eduction tubing 11 and acts uponthe well fluid 16 causing it to pass upwardly into the footpieceassembly 17 at the bottom of the eduction tubing 11. The well fluid 16is thereby caused to rise up the eduction tubing. The free pistonassembly 10 descends by gravity in the eduction tubing until it strikesthe bumper 18 supported by the spring 19 in the footpiece assembly 17. Avalve in the piston assembly closes and the gas pressures below itcauses it to move upwardly through the eduction tubing, raising a loadof well fluid above it.

3,150,596 Patented Sept. 29., 1964 ice The well fluid thus raised isdischarged through restriction valve 20 attached to the bumper housing21.

When the free piston assembly or plunger 10 moves upward into the bumperhousing 21, reaching the upper limit of its movement, a mechanical valveopener (not shown) is received within the central bore 22 of the plunger10, striking the valve element 23, moving it downwardly to open thevalve. The plunger 10 is then free to make another descent through theeduction tubing 11. A locking pin 24 with a spring 25 is provided tohold the valve in the open or closed position as said pin engages one orthe other of annular grooves 26 in valve stem 27. The magnitude of theforce supplied by spring 25 is not heavy, and the locking pin 24 iseasily disengaged from the grooves 26 by an axial force applied to saidvalve element 23.

This piston assembly 10 has a body 28 which houses the valve 23 andwhich has a number of inlet passages 29 communicating with the centralbore 22 adapted to be closed off by said valve. The upper portion of thepiston body may also be provided with expansible ring segments 30 toform a sealing contact with the eduction tubing. To the lower edge ofthe piston body 28 is threadably attached a connector 31 having a bore32 which receives valve stem 27. The upper portion of connector 31 has ashoulder 33 which supports valve 23 when the same is in the openposition as shown in FIG- URE 2.

To the lower portion of connector 31 is threadedly attached an extensiontube 34 having a central cavity 35 adapted to receive a rod 36 having anenlarged head 37. The upper portion of rod 36 is slidably positioned inbore 32 and is adapted to abut the lower end of the valve stem 27 todisengage the valve from its open position when said rod 36 is movedupward. A coil spring 38 is positioned in central cavity 35 to maintainthe rod 36 normally in the downward position so that it is spaced fromthe valve stem 27.

A sinker bar 39 is attached to the lower end of extension tube 34 by aflexible or articulated coupling 40. The flexible coupling is providedto allow the free piston assembly to bend in the event the eductiontubing 11 is not straight. The top portion of sinker bar 39 has aninterior cavity 41 receiving a coil spring 42, the top of which providesupward support for rod 36 as it abuts head 37. The sinker bar 39 isnormally longer than the plunger body 28.

The lower portion of sinker bar 39 has an axial bore 43 receiving thepush rod 44 which projects below said sinker bar 39 at 45 and has anenlarged head 46 at the other end thereof. The spring 42' is supportedby this head 46. The exterior dimension of sinker bar 39 is made smallerat 47 to facilitate the descent of the free piston through the viscouswell fluid. A helical fin 43 is provided on this smaller diametersection and extends substantially the length thereof. The purpose of thehelical fin 48 is to impart to the free piston assembly a rotatingmotion as it descends in the eduction tubing. This rotating motion,together with the increased weight of the assembly, allows the piston tofall more rapidly through the highly viscous well fluid which is oftenencountered. When the piston reaches the bottom of the well theprojection 45 of push rod 44 strikes the bumper 18. The force istransmitted up the rod 44 compressing spring 42 until it pushes on head37, whence rod 36 travels upward striking valve stem 27, disengaging thelock pin 24 from the upper groove 26 and the valve seals the bottom ofcentral bore 22. The lock pin engages lower groove 26 holdingthe valveshut. The gas pressure below it then forces the plunger 10 upwardcarrying a load of well fluid above it to the surface.

While particular embodiments of the present invention have been shownand described it will be obvious to those skilled in the art thatchanges and modifications may be made without departing from thisinvention in its broader aspects, and therefore, the aim in the appendedclaims is to cover all such changes and modifications as fall within thetrue spirit and scope of this invention.

I claim:

1. In a free piston pumping device for use in a well tubing, thecombination of: a plunger having a passage therethrough closed by anupward closing valve, the plunger having a body provided with means forslidably contacting the interior of the tubing, whereby the plunger maybe raised in the well tubing by fluid pressure below it, a sinker barfixed against axial movement relative to the body and extending downwardtherefrom, and a helical fin on the sinker bar.

2. In a free piston pumping device for use in a well tubing, thecombination of: a plunger having a passage therethrough closed by anupward closing valve, the plunger having a body provided with means forslidably contacting the interior of the tubing, whereby the plunger maybe raised in the well tubing by fiuid pressure below it, a sinker bar,and means attaching the upper end of the sinker bar to the lower end ofthe body, said means permitting universal tilting movement of the sinkerbar relative to the body.

3. In a free piston pumping device for use in a well tubing, thecombination of: a plunger having a tubular body provided with a passageextending therethrough, upward closing valve means in the body forclosing said passage, sealing means on the plunger slidably engageablewith the well tubing, whereby the plunger may be raised in the welltubing by fluid pressure below it, a sinker bar fixed against axialmovement relative to the body and extending downward therefrom, and ahelical fin on the sinker bar.

4. In a free piston pumping device for use in a well tubing, thecombination of: a plunger having a tubular body provided with a passageextending therethrough, upward valve means on the body for closing saidpassage, sealing means in the plunger slidably engageable with the welltubing, whereby the plunger may be raised in the well tubing by fluidpressure below it, a sinker bar, means attaching the upper end of thesinker bar to the lower end of the body, said means permitting universaltilting movement of the sinker bar relative to the body, and meansincluding an element extending through the interior of the sinker barfor closing said valve means.

5. In a free piston pumping device of the class having a plungerprovided with a valve and adapted to travel from the lower end of aneduction tube to a well head, the combination with said plunger of: avalve actuating means, a sinker bar having a central cavity adapted toreceive the valve actuating means, means for attaching the sinker bar tothe plunger, means resiliently supporting said valve actuating means insaid cavity, said valve actuating means having a portion thereofprojecting below said sinker bar, said sinker bar having an externalhelical fin.

6. In a free piston pumping device of the class having a plungerprovided with a valve and adapted to travel from the lower end of aneduction tube to a well head, the combination with said plunger of: anextension tube fastened to said plunger and having an axial bore, avalve actuating rod received in said bore, resilient means supportingthe valve actuating rod, a sinker bar fastened to said extension tube bya flexible coupling, said sinker bar having a central cavity in theupper portion thereof and an axially extending bore communicatingtherewith, a resilient supporting member received in said central cavityand abutting said valve actuating rod, a push rod positioned in saidaxially extending bore and projecting into said central cavity andabutting said resilient member, the lower portion of said push rodprojecting below said sinker bar, and said sinker bar having an externalhelical fin.

7. In a free piston pumping device of the class having a plungerprovided with a valve and adapted to travel from the lower end of aneduction tube to a well head, the combination of: a plunger body havinga valve therein, an extension tube attached to said body and having anaxial bore, a valve actuating rod slidably mounted in said bore andpositioned to abut the stem of said valve, said actuating rod having anenlarged lower head, a resilient member supported on said head andpositioned between the bottom of said body and said head, a sinker barattached to said extension tube and having a central cavitycommunicating with the bore of said extension tube, a second resilientmember positioned in said cavity and abutting the lower side of theaforementioned head, an axial bore in said sinker bar communieating withsaid cavity and having a push rod positioned in said bore having anenlarged upper head supporting said second resilient member, said pushrod projecting below the said sinker bar, said sinker bar having a lowercylindrical portion the diameter of which is less than that of saidextension tube, and a helical fin on said lower cylindrical portionextending substantially the entire length thereof.

References Cited in the file of this patent UNITED STATES PATENTS1,516,479 Strong Nov. 18, 1924 1,943,533 Ricker Jan. 16, 1934 1,947,587Fletcher Feb. 20, 1934 2,172,636 Coberly Sept. 12, 1939 2,267,902 EddinsDec. 30, 1941 2,642,002 Knox et al. June 16, 1953 2,970,547 McMurry Feb.7, 1961 3,044,414 Chancellor et al. July 17, 1962

1. IN A FREE PISTON PUMPING DEVICE FOR USE IN A WELL TUBING, THECOMBINATION OF: A PLUNGER HAVING A PASSAGE THERETHROUGH CLOSED BY ANUPWARD CLOSING VALVE, THE PLUNGER HAVING A BODY PROVIDED WITH MEANS FORSLIDABLY CONTACTING THE INTERIOR OF THE TUBING, WHEREBY THE PLUNGER MAYBE RAISED IN THE WELL TUBING BY FLUID PRESSURE BELOW IT, A SINKER BARFIXED AGAINST AXIAL MOVEMENT RELATIVE TO THE BODY AND EXTENDING DOWNWARDTHEREFROM, AND A HELICAL FIN ON THE SINKER BAR.